A conventional portable Karaoke system includes a microphone for converting a user's voice into an electric signal to output it through a speaker, a key unit through which a user selects a song, a display for displaying the operation state of the portable Karaoke system, and a control circuit for storing accompaniment data with respect to songs and video signals corresponding to background images and processing the stored signals. The microphone is placed on the top of a case of the portable Karaoke system, and the key unit and the display are attached to one side of the case. The control circuit is constructed on a board that is set inside the case.
The conventional portable Karaoke system radio-transmits the accompaniment sound, lyrics and background image of a song the user selects through the key unit to an image display device such as TV to display the lyrics and background image on a screen of the image display device and to output the accompaniment sound through a speaker included in the image display device. The accompaniment sound can be output through a home audio system or a car audio system and the user can sing to the accompaniment sound, holding the main body of the portable Karaoke system by the hand.
In the conventional portable Karaoke system, however, all of a circuit for radio-receiving video and audio signals, the control circuit and a transmission circuit are constructed on the board set in the case of the system. This increases the size of the board and thus the user has a difficulty in holding the portable Karaoke system by the hand to sing a song.
Furthermore, many countries including Korea increasingly put restrictions on frequencies of radio transmission devices. Thus, the portable Karaoke system cannot avoid the restrictions on the frequencies when a radio transmission circuit is constructed on the board provided in the system.
FIG. 1 is a cross-sectional view of the conventional portable Karaoke system including a modularized transmitting/receiving device. The portable Karaoke system includes a microphone 3 provided at one end of a case 1, a key unit 2 through which a user selects a song, and a display 4. The portable Karaoke system further includes an open part 10 located on one side of the case 1, an accommodating part 11 extended from the end of the case 1, a first connector 13, a transmitting/receiving module 15, and a cover 16. One end of the accommodating part 11 is opened and connected with the inside of the case 1. The first connector 13 is placed on a board 12 set inside the case 1 and protruded to the inside of the accommodating part 11. The transmitting/receiving module 15 is formed such that it can be inserted into the accommodating part 11 and includes a transmitting/receiving circuit for transmitting/receiving video and audio signals. The transmitting/receiving module 15 has a second connector 14 formed at one end thereof. The second connector 14 is connected to the first connector 13 to connect the transmitting/receiving circuit to the control circuit of the portable Karaoke system. The cover 16 covers the open part 10 of the case 1.
The transmitting/receiving module 15 further includes an FM transmitter circuit (not shown), a receiving antenna, and a radio auxiliary microphone receiver circuit (not shown). The FM transmitter circuit has a transmission antenna that modulates an audio signal output from the portable Karaoke system into a predetermined FM frequency and then transmits the modulated signal to an external FM radio. The receiving antenna receives a radio signal transmitted from a radio auxiliary microphone separated from the portable Karaoke system. The wireless auxiliary microphone receiver circuit demodulates the radio signal received by the receiving antenna and divides the demodulated signal into an audio signal and a song data signal.
A user can easily connect/disconnect the transmitting/receiving module 15 to/from the portable Karaoke system to use the system. However, since the transmitting/receiving module 15 includes both of the FM transmitter circuit and the radio auxiliary microphone receiver circuit, the user cannot select and use one of FM transmission and radio auxiliary microphone receiving functions. Furthermore, the user should purchase an unnecessary functional module. Moreover, the volume of the transmitting/receiving module 15 becomes large because it includes even the transmission antenna and the receiving antenna. Accordingly, the user has a difficulty in carrying the portable Karaoke system including the transmitting/receiving module 15.
FIG. 2 is a perspective view of a conventional portable Karaoke system having a battery housing structure. Referring to FIG. 2, the portable Karaoke system includes a case 20 a user can easily hold and a signal connecting device (not shown) for connecting the case 20 to external apparatuses (for example, an audio system, TV set and so on).
A microphone net 21 is set on the top of the case 20 and a printed circuit board 22 including various electronic components for operating the portable Karaoke system is set inside the case 20. A key input unit 23 having a plurality of key buttons (not shown) electrically connected to the printed circuit board 22 is provided on one side of the case 20. In addition, a battery case 24 for housing at least one battery for supplying power to the portable Karaoke system is arranged on the other side of the case.
The battery case 24 has a rectangular groove in which batteries are serially connected in the direction of the length thereof. Contact terminals 25 and 25′ are respectively set at both ends of the battery case to be electrically connected to the printed circuit board 22. The contact terminals 25 and 25′ are respectively made of a metal plate and a spring.
The portable Karaoke system further, includes a cover 26 for covering the case 20. The case 20 and the cover 26 are tightly combined such that a part of the case is fitted in the cover 26. An input/output terminal 27 to which a main jack of the signal connecting device is connected is formed at the bottom of the case 20.
To use the portable Karaoke system, the user inserts a predetermined battery into the battery case 24, arranging the positive and negative polarities of the battery, and combines the cover 26 with one side of the case 20. Here, a space exists between the battery in the battery case 24 and the cover 26 so that the battery is easily separated from the battery case when an external shock is applied to the case. Thus, the portable Karaoke system is not operated.
To replace the battery with a new one, the cover 26 is separated from the case 20 and the battery fitted in the battery case 24 is removed from the battery case. At this time, the battery should be separated from the battery case by putting a thin long hard substance, such as a fingernail, between the end of the battery case and the end of the battery and removing the battery. However, the user has a difficulty in removing the battery from the battery case when he/she has a short fingernail. Furthermore, the user cannot replace the battery with a new one rapidly if he/she is difficult to find a thin long hard substance.
Moreover, the conventional portable Karaoke system has a single gear formed at the end of the case, which is combined with a microphone cartridge, such that only one of a general microphone net or a ball-type microphone net can be combined with the case through the gear. Thus, the user cannot selectively use the general microphone net and the ball-type microphone net.